http://www.homebrewtalk.com/f51/love-tss2-programming-neutral-area-mode-212277/
Here's a thread I posted re: Neutral area mode w/ my TSS2 fermenteezer (hehe that's a a funny word...). I set SP1 to the set point and then SP2 is the 'margin of error' so to speak of like say 1.5 degrees. So, that way the thermal mass of the fermenter won't make a continual pass off between the freezer and the heater. It's working great for me, but as Claudius noted, not the only option. (Seriously, I do think they changed the programming characteristics of neutral area mode in the past year or so).
If I'm set at 64* and SP2 is 1.5, there is a temperature swing of 1.5 degrees in between when the freezer shuts off and the heater turns on and vice versa. You can set the SP2 to whatever is the minimum amount that you can and also prevent the continual power hand-off which would burn out the compressor.
Just 2 things slightly off topic to consider:
1) I mounted my TSS2 on the slotted removable door that covers the compressor hump. The only 2 wires that come out the back of the freezer and go into the back of the collar are the probe and heat source plug. Very clean (I hate wires) and easy to install. Just not at 'bling' height. (but you did say you already built a box... so anyhoo)
2) My sanke and corny (15g) chambers heat up very well enough with a light bulb as the heat source. I'm getting well into the highest Saison temps you'd need. I use a silicone covered 'work light' that's more bump proof than a bare light. Seriously, 100w bulb was actually too hot and I went down to 75w. I just figure I don't want hot air cooking the krausen on the fermenter on the inside, and possibly imparting flavors. Rather, I put the light bulb at mid fermenter height and it's touching the keg, so convection is handling all the heat. Dunno, just a thought.
Programing a Love TSS2-2100
Linear Mode
